With development of society and advance of science and technology, X-Ray sensors not only play an important role in the field of medical imaging, but are widely applied in other fields such as metal detection.
A conventional plane-type X-Ray sensor comprises a photosensitive array, the circuit structure of which is shown in FIG. 1. Each of the pixel units of the photosensitive array of the X-Ray sensor comprises a photodiode 11 and a thin film transistor (TFT) 12. The gate electrode of the TFT 12 is connected to a gate scanning line 13 of the X-Ray sensor, the drain electrode of the TFT 12 is connected to a data line 14 of the X-Ray sensor, and the source electrode of the TFT 12 is connected to the photodiode 11. One end of the gate scanning line 13 is connected to a scan driving circuit 16 through a connecting pin; one end of the data line 14 is connected to a data driving circuit 15 through a connecting pin.
The X-Ray sensor scans the gate signals through the scan driving circuit 16 to control the switch states of the TFTs 12 of a row of pixel units. When the TFT 12 of one pixel unit is switched on, the photocurrent signal generated by the photodiode 11 is read out sequentially through the data line 14 connected to the TFT 12 and the data driving circuit 15. The collection of the photoelectric signal is accomplished by controlling the signal timings on the gate scanning line 13 and the data line 14. That is to say, the controlling operation on the collection of the photocurrent signal generated by the photodiode 11 is accomplished by controlling the switch state of the TFT 12.
A cross-sectional view of one pixel unit in the conventional X-Ray sensor is shown in FIG. 2. Each of the pixel units sequentially from the bottom up comprises: a substrate 21, a gate layer 22, a gate insulating layer 23, an active layer 24, a source/drain electrode layer 25, a first passivation layer 26, a photoelectric conversion layer 27, an etched protection layer 28, a second passivation layer 29, a common electrode layer 30, a light blocking layer 31 and a protection layer 32. The common electrode layer 30 and the source/drain electrode layer 25 act as the two electrodes of the photodiode 11. The active layer 24 comprises an intrinsic amorphous silicon layer 241 and an n-type amorphous silicon layer 242. In a conventional preparing method, during the process of etching to form each of the gate layer 22, the gate insulating layer 23, active layer 24, the source/drain electrode layer 25, the first passivation layer 26, the photoelectric conversion layer 27, the etch protection layer 28, the second passivation layer 29, the common electrode layer 30, the light blocking layer 31 and the protection layer 32, one mask exposure process is required, and therefore the X-Ray sensor totally requires 11 photolithography processes (mask processes) during the process of manufacture, and correspondingly 11 mask plates are used for exposing photoresist.
Thus, in the conventional method for manufacturing the X-Ray sensor, the number of mask exposure is great and the manufacturing processes are very complex; furthermore, due to the high cost of a mask plate, the corresponding products have increased manufacturing costs, reduced yield and reduced productivity of equipments.